Apparatus for treating liquid with gas



W. E. GREENAWALT APPARATUS FOR TREATING LiQUID WITH GAS Filed March 21, 1924 v Patented May 4 1926.

UNITED STATES WILLIAM E. G REENAWALT, OF DENVER, COLORADO.

ArPARATns on TR-EATING LIQUIDWITI-I GAS.

Application filed March 21, 1924. Serial No. 700,833.

To all whom. it may concern:

Be it known that I, TILLIAM E. GREENA- \VALT, a citizen of the United States, residing in the city and county of Denver and State of Colorado, have invented certain new and useful Improvements in Apparatus for Treating Liquid with Gas, of which the following is a specification.

The invention has as its object the efi'ee-. tire atomization, or fine subdivision, of gas in liquid, to accomplish certain results, as

for example, the application of gas to liquid to facilitate desired chemical reactions, and in the flotation treatment of ores, as also in the pneumatic agitation of liquid and ore pulp, and in the application of corrosive gases, such as sulphur dioxide or chlorine, to the treatment of copper, gold, and silver ores.

The description of the invention will be more particularly directed to the flotation treatment of ores.

In the flotation treatment of ores excellent results have been obtained by applying air or gas to the ore pulp through porous mate- I rial in the lower-portion of the tankcontaining the ore pulp. In \doing this, certain difiicultieshave arisen, among which may be mentioned the delicate nature of the porous material if it is made of woven fabric, the clogging of the pores if inorganic porous material is used, and-the settling of the sands on the porous material and consequent unequal distribution of the air in. worn or clogged material.

To overcome these difliculties, jets of air have been injected into the liquid, and the impingement ,of the air against the liquid or against a submerged" solid obstacle subdivides the air and gives encouraging results, although these results are far from being satisfactory.

Excellent atomization. or fine subdivision, of gas in liquid is obtainable by introducing, gas and liquid into a hollow rotary member and ejecting a mixture of gas and liquid into the surrounding liquid in which the rotary member is submerged, as disclosed in my Patents No. 1,374,500, April 12, 1921, No. 1,350,605, Aug. 24, 1920, and No. 1, 374,446, April 12, 1921, but it is not always convenient to operate in that way, and the apparatus, while under excellent control, is somewhat expensive t0 install. -In the present invention it is desired to get substantially the same control and the same effective. atomization of the gas by substituting a hollow' stationary gas diffusing member for the rotary member 1n the patents re- 'ferred to.

'While some machines are more effective in atomizing gas inliquid than others, it is thought that the degree of atomization is largely-dependenton the power used. For example, from fivc'to. six pounds pressure is required to force air through a porous member to get suitable subdivision for effective flotation. This corresponds, to about a static head of twelve feet of liquid, such as water or ore pulp, if air is introduced into it through an unrestricted inlet. If a satisfactory atomization of the gas is obtainable without the use of porous membranes or rotary members it is evident that both the construction and operation of the apparatus will be simplified Primarily, the etficiency of any apparatus for treating liquid with gas is more or less proportional to the degree of subdivision of the gas,-and merely introducing a gas "into the liquid without effective subdivision would be of no advantage, no matter how simple the apparatus might be.

I have found that excellent atomization or subdivision of gas in liquid is obtainable by a combination of the principle of the air lift' and a. substantially horizontal gas diflusing upper portion with radially disposed outlets, submerged in the liquid of the tank containing the gas diffusing memher. This general arrangement gives satisclogging and without resorting to rotary mechanism. Moreover, the apparatus can be constructed in large units, and this is highly desirable, since it is cheaper and better to have a fewlarge units for a desired capacity than a multiplicity of small units. 1

The invention will now be described in detail, reference being'made. to the accompanying drawings, in which Fig. 1 represents a vertical cross section of the apparat11S;'Fig. 2 the corresponding longitudinal section; Fig. 3 a horizontal section through one compartment of the apparatus.

on the line 3-3 of Fig. 1; Fig. 4 a vertical: section of the gas atomizer or gas factory atomization and diffusion without diffusing member on an enlarged'scale; and

.Fig. a horizontal section on the line 55 of Fig. 4.

distilled into the surrounding liquid in the tank. The atomizer or gas diffusing member 5, consists of a lower vertical tube .6 communicating with a hollow upper horizontal "diffusing member 8 provided with suitable discharge'passages. A gas inlet pipe 7 communicates with the lower portion of the tube 6 and, with the blower20, which furnishes compressed air or other gas. The upper portion 8 of the atomizer 5 has radial or outwardly directed discharge passages 9 communicating with the vertical tube- 6 and with the liquid in the tank. The upper portion of the atomizer is preferably provided with a dome or space 10, which serves as a mixing chamber for the gas and liquid before the gas and liquid are ejected from the atomizer into the surrounding liquid in the tank.

The abrupt changing of the flow of gas and liquid from the vertical to the horizontal in the interior of the atomizer causes effective mixing, but themi-xing is improved by the dome 10 in the'upper portion of the atomizer. The interior of the agitating chamber 2 preferably arranged so that issuing streams 'of gas and liquid from oppositely positioned discharge passages will be difused. This is done bymeans of the deflecting projections 11 in the agitating chamber. he various compartments communicate with one another through openings 13 and 14 in the partitions 4 and openings, or commumcating passages, are preferably provided. both in the upper and lower portion of the tank. The lower openings .13' are adapted to let heavy particles in suspension in the liquid, pass from one compartment to the next, while the upper'openings 14 provide for the passage of the finer particles, or slimes. Thematerial to be. treated is fed into the inlet pipe 15 and the residue flows outthr-o'ugh the outlet pipe 17. The outletpipe 17 is preferably provided with aweir overflow 18 to take most of the liquid and fine particles and provides for a uniform liquid level in the various compartments of the tank, while the under flow 19 may take the heavier particles which cannot easily be lifted to the overflow.

The compressed air or gas is provided by the blower 20 and is supplied to the atomizers through the pipe main 21 and the the streams of issuing gas and liquid so that they commingle and give a fairly uni-- form distribution of the gas in fine particles in the ascending column of liquid in the agitating compartment. The mixing is further improved by the. projecting members 11 at thesides of the agitating chamber. ,Much the same results are obtained in this way, with a stationary atomizer or gas 'difl'using member, as are obtained with the rotary atomizer or gas diffusing member in the patents referred to. The tube 6 is preferably enlarged at its lower portion so as not to-restrict the area for'entering liquid due to the insertion of the gas pipe 7.

Assuming the tank to-be filled with ore pulp of the proper consistency and mixed with a suitable frothing agent-,the operablower is started and theamount of air delivered to the various compartments is regulated by the valves 23 to give the effect desired for each compartment, as can at once be observed by the froth produced. on the surface .of the liquid. The air, introduced into the tube 6 of the atomizer, acts as an energetic airlift for both liquid and suspended particles. When the ascendingstream of air and pulp or liquid hits the upper portion8 of the atomizer and the direction of the stream is abruptly changed, an intense mixing or atomizing action takes place and the gas and liquid is ejected from the interior of the atomizer into the surrounding liquid in the tank with the gas in finely divided bubbles. This action is intensified by the dome or mixing space 10,

since theup-rushing current of gas and liquid meets the down-rushing current in the mixing space, andamintense mixing acdesired amount to avoid excessive agitation,

or surging of the liquid at the surface,

which would iiiterfereovitli effective flotation.

The apparatus finds its best application in large units, aswill be evident from the following considerations: A low depth of liquid, and consequently a low pressure of metallurgical processes.

from the tank at a considerable velocity and the current of air and liquid will contain sutlicient energy for the effective atomization of the air in the upper portion of the atomizer. lVith such a depth of liquid, large unit installations are made possible, which is a thing to be desired in flotation, as in other Assuming an atomizer four feet in diameterand an agitating chamber six feet square with acorresponding settling chamber, it will be seen that the capacity of each compartment is approximately twenty tons of water, and if th ratio of pulverized ore to water desired for effective flotation is 1:4, each compartment will hold about five tons of ore under treatment, and if a unit tank, or installation, consists of ten compartments, fiftytons of. ore would be under treatment at one time in each unit. If the ore is given two hours treatment the daily capacity would be 600 tons, and if given one hour treatment the daily capacity would 1200., tons of ore.

Assuming a convenient compartment unit,

the number of compartments will be determined by the daily capacity desired, and-the number may range from one to ten or fifteen or even more, depending on the results desired.

The depth of submergence of the atomizer will be determined by the results desired. Ordinarily the best results for flotation will be obtained, say in a tank twelve feet deep, by having a long vertical tube or air lift so as to get as much momentum' as possible in the upward current of gas and liquid. and then eject the mixture of airand liquid from two to three feet below the surface of the liquid. This will give a positive circulation of the ore pulp and there will be no objectionable agitation or surging of the surface ot the liquid. The size of the ore particles which can be effectively circulated to prevent clogging will depend largely on the amount of air or gas circulated through the atomizer.

The apparatus can be effectively used in th treatment of ores with corrosive gases,

such as chlorine, sulphur dioxide, or ammonia. If iron is attacked by the corrosive gas or solution the atomizer may be made. of antimonial lead, ferro silicon, or any other noncorrosive substance.

The best number of discharge passages in the diffusing member 8 is determined by experiment and may vary within wide limits.

The mixture of gas and liquid is ejected in sheet-like form from the diffusing member, while the partitions forming the discharge passages give a whirling motion to the surrounding liquid in the tank to thoroughly diffuse the gas in the tank liquid.

I claim:

1. In apparatus for treating liquid with gas, a tank adapted to contain liquid, a hollowstationary gas difiusing member within the tank submerged in the liquid comprising a vertical tube with its lower end in communication with the tank and its upper end in communication with outwardly directed discharge passages adapted to discharge gas and liquid from the interior of the hollow gas dili'using member indifferent directions into the surrounding liquid in the tank, and means for supplying gas to the interior of said vertical tube.

2. In apparatus for treating liquid with gas, a tank adapted to contain liquid, a stationary hollow gas diliusing member having curved, substantially radially disposed discharge passages within the tank submerged in the liquid and adapted to eject a mixture of gas and liquid from its interior into the surrounding liquid in the tank, means to deliver gas and liquid into said diffusing member, said radial discharge passages being curved so that streams of gas and liquid issuing therefrom will impart a swirling motion to the surrounding liquid in the tank, and means for supplying gas to the interior of the hollow gas diffusing member.

' 3. In apparatus for treating liquid with gas, .a tank adapted to contain liquid, :1. hollow stationary member within the tank submerged in the liquid comprising a vertical tube open at its lower end and communicating with outwardly directed discha go passages at its upper end. means for introducing gas andliquid through the tube into the interior. of the hollow gas dill'using member.

and means adapted {for mixing the gas and liquid within thegas diil'using member.

4. In apparatus for treating liquid with gas, a tank adapted to contain liquid. :1 hollow stationary gas dill'nsing member comprising a vertical tube communicating with outwardly disposed discharge passages at its upper end and with the tank at its lower end and a dome or chamber communicating with both the vertical tube. and with the discharge passages, and means for delivering gas to the interior of the vertical .tube.

5. In apparatus for treating liquid with gas, atank adapted to contain liquid, :1. hollow stationary gas diilusing member submerged in the liquid comprising a vertical tube communicating with the tank at lts lower end and with a submerged fluid receiving member at .its upper end, said fluid receiving member being adapted to receive gas and'liquid from the vertical tube and difiuse the gas and liquid in different directions into the surrounding liquid in the tank,

and-means for delivering gas into the interior of the vertical tube.

6. In apparatus for treating liquid with gas, a tank adapted to contain liquid divided into an agitating chamber and a settling chamber, the-bottom of said agitating chamber being in communication with the settling chamber, a hollow stationary gas ditlusing member submerged in the liquid comprising a vertical tube communicating with the settling chamber at its lower endand with a submerged fluid receiving member at its upper end, said fluid receiving member being located'withm the agitating chamber and adapted to receive'gas and gas, a tank adapted to contain liquid, a sta tionary hollow gas diffusing-member comprising means for receiving separate streams of gas and liquid in the lower portion of the tank' and discharge outlets for ejecting a mixture of gas and liquid into the surrounding liquid in the upper portion of the tank,

- and horizontal stationary deflectin member's arranged in proximity to .thed scharg'e outlets'adapted to deflect opposite streams of issuing-gas and liquid coward one another so that they will mix and be diflused in the liquid in the tank. 8. In apparatus for treating liquid with gas, a tank adapted to contain liquid, a hollow. stationary gas diffusing member submerged in the liquid comprising a vertical tube open at'its lower end and communieating with a. mixing chamber at its upper end sald mixing chambercommunicating with outwardly directed discharge passages,

and means for delivering gas to the interior of the vertical tube.

9. In apparatus for treating liquid with gas, a tank adapted to contain liquid, a hol--- low stationary gas dilfu'sing member within the tank submerged-in the liquid comprising a mixing chamber a vertical tube communicating with the lower. portion of the tank and with the mixing chamber and oppositely positioned discharge passages communicating with the mixing chamber and with the upper portion of the tank, and means for delivering gas to the interior of the vertical tube.

.10. In apparatus for treating liquid with gas a tank adapted to contain liquid, a hollow stationary gas difiusing member within the tank submerged in the liquid comprising a vertical tube withits lower end incommunication with the tank' and its upper end in communication with outwardly directed discharge passages adapted to discharge gas and liquid in sheet-like form into the surrounding-liquid in the tank, and means for supplying gas to the interior of said verticaltub'e.

11. In apparatus for treating liquid with gas, a tank adapted to contain liquid divided into an agitating chamber and a settling chamber the bottom of said agitating enamb'er being in communication with the set tling chamber, a hollow stationary gas diffusing member within the tank comprising a vertical tube communicating with the settling chamber at 'its lower. end and with a fluid receiving member at its upper end, said fluid'receiving member being located With-- in the agitating chamber and adapted to re ceive gas and liquid from the vertical tube and diffuse the gas and liquid in different directions in the agitating chamber, and means for delivering gas into the interior of the vertical tube.

- WILLIAM E. GREENAWALT. 

